Systems, apparatuses, and methods for cumulative summation

ABSTRACT

Systems, methods, and apparatuses for executing an instruction are described. For example, an instruction includes at least an opcode, a field for a packed data source operand, and a field for a packed data destination operand. When executed, the instruction causes for each data element position of the source operand, add to a value stored in that data element position all values stored in preceding data element positions of the packed data source operand and store a result of the addition into a corresponding data element position of the packed data destination operand.

FIELD OF INVENTION

The field of invention relates generally to computer processorarchitecture, and, more specifically, to an instruction which whenexecuted causes a particular result.

BACKGROUND

An instruction set, or instruction set architecture (ISA), is the partof the computer architecture related to programming, and may include thenative data types, instructions, register architecture, addressingmodes, memory architecture, interrupt and exception handling, andexternal input and output (I/O). It should be noted that the terminstruction generally refers herein to a macro-instruction—that isinstructions that are provided to the processor for execution—as opposedto micro-instructions or micro-ops—that result from a processor'sdecoder decoding macro-instructions).

The instruction set architecture is distinguished from themicroarchitecture, which is the internal design of the processorimplementing the ISA. Processors with different microarchitectures canshare a common instruction set. For example, Intel Pentium 4 processors,Intel Core processors, and Advanced Micro Devices, Inc. of SunnyvaleCalif. processors implement nearly identical versions of the x86instruction set (with some extensions having been added to newerversions), but have different internal designs. For example, the sameregister architecture of the ISA may be implemented in different ways indifferent microarchitectures using well known techniques, includingdedicated physical registers, one or more dynamically allocated physicalregisters using a register renaming mechanism (e.g., the use of aRegister Alias Table (RAT), a Reorder Buffer (ROB) and a retirementregister file as described in U.S. Pat. No. 5,446,912; the use ofmultiple maps and a pool of registers as described in U.S. Pat. No.5,207,132), etc. Unless otherwise specified, the phrases registerarchitecture, register file, and register refer to that which is visibleto the software/programmer and the manner in which instructions specifyregisters. Where specificity is desired, the adjective logical,architectural, or software visible will be used to indicateregisters/files in the register architecture, while different adjectiveswill be used to designate registers in a given microarchitecture (e.g.,physical register, reorder buffer, retirement register, register pool).

An instruction set includes one or more instruction formats. A giveninstruction format defines various fields (number of bits, location ofbits) to specify, among other things, the operation to be performed andthe operand(s) on which that operation is to be performed. A giveninstruction is expressed using a given instruction format and specifiesthe operation and the operands. An instruction stream is a specificsequence of instructions, where each instruction in the sequence is anoccurrence of an instruction in an instruction format.

Scientific, financial, auto-vectorized general purpose, RMS(recognition, mining, and synthesis)/visual and multimedia applications(e.g., 2D/3D graphics, image processing, videocompression/decompression, voice recognition algorithms and audiomanipulation) often require the same operation to be performed on alarge number of data items (referred to as “data parallelism”). SingleInstruction Multiple Data (SIMD) refers to a type of instruction thatcauses a processor to perform the same operation on multiple data items.SIMD technology is especially suited to processors that can logicallydivide the bits in a register into a number of fixed-sized dataelements, each of which represents a separate value. For example, thebits in a 64-bit register may be specified as a source operand to beoperated on as four separate 16-bit data elements, each of whichrepresents a separate 16-bit value. As another example, the bits in a256-bit register may be specified as a source operand to be operated onas four separate 64-bit packed data elements (quad-word (Q) size dataelements), eight separate 32-bit packed data elements (double word (D)size data elements), sixteen separate 16-bit packed data elements (word(W) size data elements), or thirty-two separate 8-bit data elements(byte (B) size data elements). This type of data is referred to as thepacked data type or vector data type, and operands of this data type arereferred to as packed data operands or vector operands. In other words,a packed data item or vector refers to a sequence of packed dataelements; and a packed data operand or a vector operand is a source ordestination operand of a SIMD instruction (also known as a packed datainstruction or a vector instruction).

By way of example, one type of SIMD instruction specifies a singlevector operation to be performed on two source vector operands in avertical fashion to generate a destination vector operand (also referredto as a result vector operand) of the same size, with the same number ofdata elements, and in the same data element order. The data elements inthe source vector operands are referred to as source data elements,while the data elements in the destination vector operand are referredto a destination or result data elements. These source vector operandsare of the same size and contain data elements of the same width, andthus they contain the same number of data elements. The source dataelements in the same bit positions in the two source vector operandsform pairs of data elements (also referred to as corresponding dataelements; that is, the data element in data element position 0 of eachsource operand correspond, the data element in data element position 1of each source operand correspond, and so on). The operation specifiedby that SIMD instruction is performed separately on each of these pairsof source data elements to generate a matching number of result dataelements, and thus each pair of source data elements has a correspondingresult data element. Since the operation is vertical and since theresult vector operand is the same size, has the same number of dataelements, and the result data elements are stored in the same dataelement order as the source vector operands, the result data elementsare in the same bit positions of the result vector operand as theircorresponding pair of source data elements in the source vectoroperands. In addition to this exemplary type of SIMD instruction, thereare a variety of other types of SIMD instructions (e.g., that have onlyone or has more than two source vector operands; that operate in ahorizontal fashion; that generate a result vector operand that is of adifferent size, that have a different size of data elements, and/or thathave a different data element order). It should be understood that theterm destination vector operand (or destination operand) is defined asthe direct result of performing the operation specified by aninstruction, including the storage of that destination operand at alocation (be it a register or at a memory address specified by thatinstruction) so that it may be accessed as a source operand by anotherinstruction (by specification of that same location by the anotherinstruction.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereferences indicate similar elements and in which:

FIG. 1 illustrates an embodiment of hardware to process a cumsuminstruction;

FIG. 2 illustrates an example of an execution of a cumsum instructionaccording to an embodiment;

FIG. 3 illustrates an example of an execution of a cumsum instructionaccording to an embodiment;

FIG. 4 illustrates embodiments of the cumsum instruction;

FIG. 5 illustrates an embodiment of method performed by a processor toprocess a cumsum instruction;

FIG. 6 illustrates an embodiment of the execution portion of the methodperformed by a processor to process a cumsum instruction;

FIGS. 7A-7B are block diagrams illustrating a generic vector friendlyinstruction format and instruction templates thereof according toembodiments of the invention;

FIGS. 8A-D are block diagrams illustrating an exemplary specific vectorfriendly instruction format according to embodiments of the invention;

FIG. 9 is a block diagram of a register architecture according to oneembodiment of the invention;

FIG. 10A is a block diagram illustrating both an exemplary in-orderpipeline and an exemplary register renaming, out-of-orderissue/execution pipeline according to embodiments of the invention;

FIG. 10B is a block diagram illustrating both an exemplary embodiment ofan in-order architecture core and an exemplary register renaming,out-of-order issue/execution architecture core to be included in aprocessor according to embodiments of the invention;

FIGS. 11A-B illustrate a block diagram of a more specific exemplaryin-order core architecture, which core would be one of several logicblocks (including other cores of the same type and/or different types)in a chip;

FIG. 12 is a block diagram of a processor 1200 that may have more thanone core, may have an integrated memory controller, and may haveintegrated graphics according to embodiments of the invention;

FIGS. 13-16 are block diagrams of exemplary computer architectures; and

FIG. 17 is a block diagram contrasting the use of a software instructionconverter to convert binary instructions in a source instruction set tobinary instructions in a target instruction set according to embodimentsof the invention.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth.However, it is understood that embodiments of the invention may bepracticed without these specific details. In other instances, well-knowncircuits, structures and techniques have not been shown in detail inorder not to obscure the understanding of this description.

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

A cumulative sum is a sequence of partial sums of a given sequence. Forexample, the cumulative sums of the sequence {a,b,c, . . . }, are a,a+b, a+b+c, etc. For loops where the value of the current iterationdepends on previous iterations, efficient horizontal cumulative sum andproduct can potentially allow for profitable vectorization despite theloop carried dependency. As a simple example, consider the followingloop:

int v = 0;    for (int i = 0; i < 8; ++i) {       a[i] = v + fun(i);      v = a[i];    }where fun(i) represents some vectorizable function to calculate a valuebased on the loop index. In this example, the value for a indexed by idepends on the value in the previous iteration creating a dependencythat makes efficient vectorization difficult. With a single instruction,multiple data (SIMD) extension (e.g., cumsum) for horizontal cumulativesum, the loop can be vectorized with a single instruction to handle theloop-carried data dependency that can be optimized in hardware.

A more practical example of the problem occurs in machine learningalgorithms for the induction of decision trees. The decision treealgorithms recursively search for split points for features that bestclassify the output data. For example, a streaming video service mightpredict that one will enjoy a movie only if younger than 13 years ofage. In the training process, each split point for the feature (e.g.,age) is evaluated (up to N−1 split points for N records). For each splitpoint, some metric (e.g., information gain based on Shannon entropy,GINI, etc.) is calculated based on the how the output classes would besplit (e.g., <25 years, 43% enjoyed the movie). In order to evaluatemany possible split points efficiently, each feature is sorted by value.The loop over the sorted data allows for rapid update of the classcounts used in the split metric, but also introduces multipleloop-carried dependencies. A code listing for the GINI calculation fromthe ScalParC decision tree algorithm in NU-Minebench 2.0 is shown below.In the listing, j indexes the class label for that record. Loopdependencies for Cabove, Cbelow, split_above, and split_below exist.

Depending on the number of classes, conflict detection algorithms (highnumber of classes relative to vector width) might perform best forCabove, Cbelow dependencies and cumulative sum for a small number ofclasses that can be kept in register. Cumulative sum operations can beused to address the dependencies in split_above and split_below. Thescalar update to find the maximum split point (mgini, spointer) can behandled with predication to calculate per-lane maxima with a reductionat the end of the loop as shown below.

for(i=0;i<size−1;i++) {    j = Recs[i].cid;    v1 −= 1.0;    v2 += 1.0;   k = (double)Cabove[j];    l = (double)Cbelow[j];    split_above +=1.0−2.0*k;    split_below += 1.0+2.0*l;    Cabove[j]−−;    Cbelow[j]++;   if (Recs[i].val != Recs[i+1].val) {       gini = 1.0 −split_above/(v1*v) − split_below/(v2*v);          if(gini < mgini) {            mgini = gini;             *spointer = i+1;          }      }    }

Detailed herein are embodiments apparatuses, systems, and methods usinga cumulative-sum (“cumsum”) instruction that when executed by a hardwareprocessor causes a cumulative sum to be calculated for each data elementposition of a packed data source operand and stored in a correspondingdata element position of a packed data destination operand.

FIG. 1 illustrates an embodiment of hardware to process a cumsuminstruction. The illustrated hardware is typically a part of a hardwareprocessor or core such as a part of a central processing unit,accelerator, etc.

A cumsum instruction is received by decode circuitry 101. For example,the decode circuitry 101 receives this instruction from fetchlogic/circuitry. The cumsum instruction includes fields for a sourceoperand (e.g., a packed data register (sometimes called a vectorregister) or a memory location) and a destination operand (e.g., apacked data register (sometimes called a vector register) or a memorylocation). More detailed embodiments of instruction formats will bedetailed later.

The decode circuitry 101 decodes the cumsum instruction into one or moreoperations. In some embodiments, this decoding includes generating aplurality of micro-operations to be performed by execution circuitry(such as execution circuitry 109). The decode circuitry 101 also decodesinstruction prefixes.

In some embodiments, register renaming, register allocation, and/orscheduling circuitry 103 provides functionality for one or more of: 1)renaming logical operand values to physical operand values (e.g., aregister alias table in some embodiments), 2) allocating status bits andflags to the decoded instruction, and/or 3) scheduling the decodedinstruction for execution on execution circuitry out of an instructionpool (e.g., using a reservation station in some embodiments).

Registers (register file) 105 and memory 107 store data as operands ofthe cumsum instruction to be operated on by execution circuitry 109.Exemplary register types include packed data registers, general purposeregisters, and floating point registers. The registers 105 may alsoinclude write mask registers as detailed herein.

Execution circuitry 109 executes the decoded cumsum instruction tocalculate a cumulative sum for each data element position of a packeddata source operand and store it in a corresponding data elementposition of a packed data destination operand.

In some embodiments, retirement circuitry 111 architecturally commitsresult (e.g., commits a destination register into the registers 105) andretires the instruction.

FIG. 2 illustrates an example of an execution of a cumsum instructionaccording to an embodiment. This example is not meant to be limiting.For example, while this example uses a little endian format, theteachings herein allow for a big endian format execution.

Typically, the number of packed data elements to extract and their sizesis dependent upon the instruction encoding (data element size). As such,a different number of packed data elements such as 2, 4, 8, 16, 32, or64 may be in a packed data source. Packed data destination registersizes include 64-bit, 128-bit, 256-bit, and 512-bit.

In this example, the source 201 (e.g., a packed data register or memorylocation) includes four packed data elements. The least significant dataelement position stores a “2” as its value and the most significant dataelement position stores a “10” as its value. These values are shown asdecimal, however, they are typically stored as binary or hexadecimalvalues.

Arithmetic circuitry 203 (called “ADD CIRCUITRY” in the illustration toemphasis that an addition is being performed), such as an arithmeticlogic unit, is used to perform additions. In particular, a value fromeach data element position of the source 201 is added to all of thevalues of preceding data element positions. For example, in the least issignificant data element position, there is no addition needed as thereare no preceding data elements positions. However, for the second mostleast significant data element position the values of that position (1in this example) is added to the values stored in the data elementpositions that precede it (in this example, 2 is added to 1). In someembodiments, the independent arithmetic circuitry is used for theadditions. In other embodiments, the same arithmetic circuitry is usedfor the additions.

The result of each addition (or in the case of the least significantdata element position no addition) is stored in a corresponding dataelement position in the destination 205 (e.g., a packed data register ormemory location).

FIG. 3 illustrates an example of an execution of a cumsum instructionaccording to an embodiment. This example is not meant to be limiting.For example, while this example uses a little endian format, theteachings herein allow for a big endian format execution.

Typically, the number of packed data elements to extract and their sizesis dependent upon the instruction encoding (data element size). As such,a different number of packed data elements such as 2, 4, 8, 16, 32, or64 may be in a packed data source. Packed data destination registersizes include 64-bit, 128-bit, 256-bit, and 512-bit.

In this example, the source 301 (e.g., a packed data register or memorylocation) includes four packed data elements. The least significant dataelement position stores a “2” as its value and the most significant dataelement position stores a “10” as its value. These values are shown asdecimal, however, they are typically stored as binary or hexadecimalvalues.

Arithmetic circuitry 303 (called “ADD CIRCUITRY” in the illustration toemphasis that an addition is being performed), such as an arithmeticlogic unit, is used to perform additions. In particular, a value fromeach data element position of the source 301 is added to all of thevalues of preceding data element positions. For example, in the least issignificant data element position, there is no addition needed as thereare no preceding data elements positions. However, for the second mostleast significant data element position the values of that position (1in this example) is added to the values stored in the data elementpositions that precede it (in this example, 2 is added to 1). In someembodiments, the independent arithmetic circuitry is used for theadditions. In other embodiments, the same arithmetic circuitry is usedfor the additions.

The result of each addition (or in the case of the least significantdata element position no addition) is stored in a corresponding dataelement position in the destination 305 (e.g., a packed data register ormemory location) according to values of a mask 307 (such as a writemaskregister detailed herein). For example, when a corresponding dataelement position of the mask 307 is a “1” then the result is writteninto the destination. When the corresponding data element position ofthe mask 307 is a “0” then the result is not written into thedestination. Of course, a convention using “0” as the indication towrite made be used.

An embodiment of a format (including fields) for a cumsum instruction iscumsum{B/W/D/Q}{k} DST/SRC. In some embodiments, cumsum {B/W/D/Q} is theopcode of the instruction. B/W/D/Q indicates the data element sizes ofthe sources/destination as byte, word, doubleword, and quadword. DST/SRCis a packed data source and destination register. K is a writemask thatis used in some embodiments as detailed herein.

Another embodiment of a format (including fields) for a cumsuminstruction is cumsum{B/W/D/Q}{k} DST, SRC. In some embodiments,cumsum{B/W/D/Q} is the opcode of the instruction. B/W/D/Q indicates thedata element sizes of the sources/destination as byte, word, doubleword,and quadword. DST is a packed data destination register and SRC is apacked data source register. K is a writemask that is used in someembodiments as detailed herein.

Another embodiment of a format (including fields) for a cumsuminstruction is cumsum{B/W/D/Q}{k} DST, SRCMEM. In some embodiments,cumsum{B/W/D/Q} is the opcode of the instruction. B/W/D/Q indicates thedata element sizes of the sources/destination as byte, word, doubleword,and quadword. DST is a packed data destination register and SRCMEM is asource memory location. K is a writemask that is used in someembodiments as detailed herein.

Another embodiment of a format (including fields) for a cumsuminstruction is cumsum{B/W/D/Q}{k} DSTMEM, SRCMEM. In some embodiments,cumsum {B/W/D/Q} is the opcode of the instruction. B/W/D/Q indicates thedata element sizes of the sources/destination as byte, word, doubleword,and quadword. DSTMEM is a destination memory location and SRCMEM is asource memory location. K is a writemask that is used in someembodiments as detailed herein.

Another embodiment of a format (including fields) for a cumsuminstruction is cumsum{B/W/D/Q}{k} DSTMEM, SRC. In some embodiments,cumsum {B/W/D/Q} is the opcode of the instruction. B/W/D/Q indicates thedata element sizes of the sources/destination as byte, word, doubleword,and quadword. DSTMEM is a destination memory location and SRC is asource packed data register. K is a writemask that is used in someembodiments as detailed herein.

In embodiments, encodings of the instructions include a scale-index-base(SIB) type memory addressing operand that indirectly identifies multipleindexed destination locations in memory. In one embodiment, an SIB typememory operand includes an encoding identifying a base address register.The contents of the base address register represent a base address inmemory from which the addresses of the particular destination locationsin memory are calculated. For example, the base address is the addressof the first location in a block of potential destination locations foran extended vector instruction. In one embodiment, an SIB type memoryoperand includes an encoding identifying an index register. Each elementof the index register specifies an index or offset value usable tocompute, from the base address, an address of a respective destinationlocation within a block of potential destination locations. In oneembodiment, an SIB type memory operand includes an encoding specifying ascaling factor to be applied to each index value when computing arespective destination address. For example, if a scaling factor valueof four is encoded in the SIB type memory operand, each index valueobtained from an element of the index register is multiplied by four andthen added to the base address to compute a destination address.

In one embodiment, an SIB type memory operand of the form vm32{x,y,z}identifies a vector array of memory operands specified using SIB typememory addressing. In this example, the array of memory addresses isspecified using a common base register, a constant scaling factor, and avector index register containing individual elements, each of which is a32-bit index value. The vector index register may be an XMM register(vm32x), a YMM register (vm32y), or a ZMM register (vm32z). In anotherembodiment, an SIB type memory operand of the form vm64{x,y,z}identifies a vector array of memory operands specified using SIB typememory addressing. In this example, the array of memory addresses isspecified using a common base register, a constant scaling factor, and avector index register containing individual elements, each of which is a64-bit index value. The vector index register may be an XMM register(vm64x), a YMM register (vm64y) or a ZMM register (vm64z).

In some embodiments, the cumsum instruction includes a writemaskregister operand. A writemask is used to conditionally controlper-element operations and updating of results. Depending upon theimplementation, the writemask uses merging or zeroing masking.Instructions encoded with a predicate (writemask, write mask, or kregister) operand use that operand to conditionally control per-elementcomputational operation and updating of result to the destinationoperand. The predicate operand is known as the opmask (writemask)register. The opmask is a set of eight architectural registers of sizeMAX_KL (64-bit). Note that from this set of 8 architectural registers,only k1 through k7 can be addressed as predicate operand. k0 can be usedas a regular source or destination but cannot be encoded as a predicateoperand. Note also that a predicate operand can be used to enable memoryfault-suppression for some instructions with a memory operand (source ordestination). As a predicate operand, the opmask registers contain onebit to govern the operation/update to each data element of a vectorregister. In general, opmask registers can support instructions withelement sizes: single-precision floating-point (float32), integerdoubleword(int32), double-precision floating-point (float64), integerquadword (int64). The length of a opmask register, MAX_KL, is sufficientto handle up to 64 elements with one bit per element, i.e. 64 bits. Fora given vector length, each instruction accesses only the number ofleast significant mask bits that are needed based on its data type. Anopmask register affects an instruction at per-element granularity. So,any numeric or non-numeric operation of each data element andper-element updates of intermediate results to the destination operandare predicated on the corresponding bit of the opmask register. In mostembodiments, an opmask serving as a predicate operand obeys thefollowing properties: 1) the instruction's operation is not performedfor an element if the corresponding opmask bit is not set (this impliesthat no exception or violation can be caused by an operation on amasked-off element, and consequently, no exception flag is updated as aresult of a masked-off operation); 2). a destination element is notupdated with the result of the operation if the corresponding writemaskbit is not set. Instead, the destination element value must be preserved(merging-masking) or it must be zeroed out (zeroing-masking); 3) forsome instructions with a memory operand, memory faults are suppressedfor elements with a mask bit of 0. Note that this feature provides aversatile construct to implement control-flow predication as the mask ineffect provides a merging behavior for vector register destinations. Asan alternative the masking can be used for zeroing instead of merging,so that the masked out elements are updated with 0 instead of preservingthe old value. The zeroing behavior is provided to remove the implicitdependency on the old value when it is not needed.

FIG. 4 illustrates embodiments of the cumsum instruction includingfields for the opcode 401, destination operand 403, source operand 405(as needed), and, in some embodiments, a writemask operand 407.

FIG. 5 illustrates an embodiment of method performed by a processor toprocess a cumsum instruction.

At 501, an instruction is fetched. For example, a cumsum instruction isfetched. The cumsum instruction includes fields for an opcode, and apacked data source and destination operand. In some embodiments, thecumsum instruction includes field for a writemask operand. In someembodiments, the instruction is fetched from an instruction cache.

The fetched instruction is decoded at 503. For example, the fetchedcumsum instruction is decoded by decode circuitry such as that detailedherein. In some embodiments, the instruction is decoded into one or moremicro-operations.

Data associated with the source operand of the decoded instruction isretrieved at 505. For example, contiguous elements from memory areaccessed beginning at the source address or a source and/or destinationpacked data register is accessed.

At 507, the decoded instruction is executed by execution circuitry(hardware) such as that detailed herein. For the cumsum instruction, theexecution will, for each data element position of the packed data sourceoperand, add to a value stored in that data element position all valuesstored in preceding data element positions of the packed data sourceoperand and store a result of the addition into a corresponding dataelement position of the packed data destination operand. In someembodiments, the storage of each result is dependent upon a writemaskvalue at a corresponding position in a writemask. Depending upon theembodiment, the additions may be done serially or in parallel.

In some embodiments, the instruction is committed or retired at 509.

FIG. 6 illustrates an embodiment of the execution portion of the methodperformed by a processor to process a cumsum instruction.

At 601, a value of a first data element position of the source operandis stored into the destination operand at a data element position thatcorresponds to the first data element position of the source operand.For example, a value from a least significant data element position ofthe source operand (such as a packed data register or memory location)is stored into a least significant data element position of thedestination operand (such as a packed data register or memory location).An example of this is shown in FIG. 2 of “2” being stored from the leastsignificant data element position of the source 201 into the destination205.

The value from the first data element position of the source is added toa value from a second (subsequent) data element position of the sourcethat is immediately adjacent to, and larger than, the first data elementposition of the source at 603. For example, the value of next most leastsignificant data element of the source is added to the value of theleast significant data element position of the source. An example ofthis is shown in FIG. 2 of “2” being added to “1” from the source 201.

The result of the addition of 603 is stored and stored into thedestination at a data element position that corresponds to the largerdata element position 205. An example of this is shown in FIG. 2 of “2”being added to “1” from the source 201 and stored as “3” into the dataelement position of the destination that corresponds to the next mostleast significant data element of the source. In some embodiments, thisstorage is subject to a writemask as detailed earlier.

A determination of if all data element positions in the source have beenevaluated (have been subjected to an add if necessary) is made at 607.

When all of the data element positions have been evaluated, then theexecution has completed. When not all of the data element positions havebeen evaluated, a value from the addition of 603 is added to a valuefrom a next data element position of the source that is immediatelyadjacent to, and larger than, the subsequent data element position of603 at 609.

The result of the addition of 609 is stored and stored into thedestination at a data element position that corresponds to the largerdata element position. In some embodiments, this storage is subject to awritemask as detailed earlier. A determination of if all data elementpositions in the source have been evaluated (have been subjected to anadd if necessary) is made at 607.

The figures below detail exemplary architectures and systems toimplement embodiments of the above. In some embodiments, one or morehardware components and/or instructions described above are emulated asdetailed below, or implemented as software modules.

Embodiments of the instruction(s) detailed above are embodied may beembodied in a “generic vector friendly instruction format” which isdetailed below. In other embodiments, such a format is not utilized andanother instruction format is used, however, the description below ofthe writemask registers, various data transformations (swizzle,broadcast, etc.), addressing, etc. is generally applicable to thedescription of the embodiments of the instruction(s) above.Additionally, exemplary systems, architectures, and pipelines aredetailed below. Embodiments of the instruction(s) above may be executedon such systems, architectures, and pipelines, but are not limited tothose detailed.

An instruction set may include one or more instruction formats. A giveninstruction format may define various fields (e.g., number of bits,location of bits) to specify, among other things, the operation to beperformed (e.g., opcode) and the operand(s) on which that operation isto be performed and/or other data field(s) (e.g., mask). Someinstruction formats are further broken down though the definition ofinstruction templates (or subformats). For example, the instructiontemplates of a given instruction format may be defined to have differentsubsets of the instruction format's fields (the included fields aretypically in the same order, but at least some have different bitpositions because there are less fields included) and/or defined to havea given field interpreted differently. Thus, each instruction of an ISAis expressed using a given instruction format (and, if defined, in agiven one of the instruction templates of that instruction format) andincludes fields for specifying the operation and the operands. Forexample, an exemplary ADD instruction has a specific opcode and aninstruction format that includes an opcode field to specify that opcodeand operand fields to select operands (source1/destination and source2);and an occurrence of this ADD instruction in an instruction stream willhave specific contents in the operand fields that select specificoperands. A set of SIMD extensions referred to as the Advanced VectorExtensions (AVX) (AVX1 and AVX2) and using the Vector Extensions (VEX)coding scheme has been released and/or published (e.g., see Intel® 64and IA-32 Architectures Software Developer's Manual, September 2014; andsee Intel® Advanced Vector Extensions Programming Reference, October2014).

Exemplary Instruction Formats

Embodiments of the instruction(s) described herein may be embodied indifferent formats. Additionally, exemplary systems, architectures, andpipelines are detailed below. Embodiments of the instruction(s) may beexecuted on such systems, architectures, and pipelines, but are notlimited to those detailed.

Generic Vector Friendly Instruction Format

A vector friendly instruction format is an instruction format that issuited for vector instructions (e.g., there are certain fields specificto vector operations). While embodiments are described in which bothvector and scalar operations are supported through the vector friendlyinstruction format, alternative embodiments use only vector operationsthe vector friendly instruction format.

FIGS. 7A-7B are block diagrams illustrating a generic vector friendlyinstruction format and instruction templates thereof according toembodiments of the invention. FIG. 7A is a block diagram illustrating ageneric vector friendly instruction format and class A instructiontemplates thereof according to embodiments of the invention; while FIG.7B is a block diagram illustrating the generic vector friendlyinstruction format and class B instruction templates thereof accordingto embodiments of the invention. Specifically, a generic vector friendlyinstruction format 700 for which are defined class A and class Binstruction templates, both of which include no memory access 705instruction templates and memory access 720 instruction templates. Theterm generic in the context of the vector friendly instruction formatrefers to the instruction format not being tied to any specificinstruction set.

While embodiments of the invention will be described in which the vectorfriendly instruction format supports the following: a 64 byte vectoroperand length (or size) with 32 bit (4 byte) or 64 bit (8 byte) dataelement widths (or sizes) (and thus, a 64 byte vector consists of either16 doubleword-size elements or alternatively, 8 quadword-size elements);a 64 byte vector operand length (or size) with 16 bit (2 byte) or 8 bit(1 byte) data element widths (or sizes); a 32 byte vector operand length(or size) with 32 bit (4 byte), 64 bit (8 byte), 16 bit (2 byte), or 8bit (1 byte) data element widths (or sizes); and a 16 byte vectoroperand length (or size) with 32 bit (4 byte), 64 bit (8 byte), 16 bit(2 byte), or 8 bit (1 byte) data element widths (or sizes); alternativeembodiments may support more, less and/or different vector operand sizes(e.g., 256 byte vector operands) with more, less, or different dataelement widths (e.g., 128 bit (16 byte) data element widths).

The class A instruction templates in FIG. 7A include: 1) within the nomemory access 705 instruction templates there is shown a no memoryaccess, full round control type operation 710 instruction template and ano memory access, data transform type operation 715 instructiontemplate; and 2) within the memory access 720 instruction templatesthere is shown a memory access, temporal 725 instruction template and amemory access, non-temporal 730 instruction template. The class Binstruction templates in FIG. 7B include: 1) within the no memory access705 instruction templates there is shown a no memory access, write maskcontrol, partial round control type operation 712 instruction templateand a no memory access, write mask control, vsize type operation 717instruction template; and 2) within the memory access 720 instructiontemplates there is shown a memory access, write mask control 727instruction template.

The generic vector friendly instruction format 700 includes thefollowing fields listed below in the order illustrated in FIGS. 7A-7B.

Format field 740—a specific value (an instruction format identifiervalue) in this field uniquely identifies the vector friendly instructionformat, and thus occurrences of instructions in the vector friendlyinstruction format in instruction streams. As such, this field isoptional in the sense that it is not needed for an instruction set thathas only the generic vector friendly instruction format.

Base operation field 742—its content distinguishes different baseoperations.

Register index field 744—its content, directly or through addressgeneration, specifies the locations of the source and destinationoperands, be they in registers or in memory. These include a sufficientnumber of bits to select N registers from a PxQ (e.g. 32x512, 16x128,32x1024, 64x1024) register file. While in one embodiment N may be up tothree sources and one destination register, alternative embodiments maysupport more or less sources and destination registers (e.g., maysupport up to two sources where one of these sources also acts as thedestination, may support up to three sources where one of these sourcesalso acts as the destination, may support up to two sources and onedestination).

Modifier field 746—its content distinguishes occurrences of instructionsin the generic vector instruction format that specify memory access fromthose that do not; that is, between no memory access 705 instructiontemplates (746A) and memory access 720 instruction templates. Memoryaccess operations read and/or write to the memory hierarchy (in somecases specifying the source and/or destination addresses using values inregisters), while non-memory access operations do not (e.g., the sourceand destinations are registers). While in one embodiment this field alsoselects between three different ways to perform memory addresscalculations, alternative embodiments may support more, less, ordifferent ways to perform memory address calculations.

Augmentation operation field 750—its content distinguishes which one ofa variety of different operations to be performed in addition to thebase operation. This field is context specific. In one embodiment of theinvention, this field is divided into a class field 768, an alpha field752, and a beta field 754. The augmentation operation field 750 allowscommon groups of operations to be performed in a single instructionrather than 2, 3, or 4 instructions.

Scale field 760—its content allows for the scaling of the index field'scontent for memory address generation (e.g., for address generation thatuses 2^(scale)*index+base).

Displacement Field 762A—its content is used as part of memory addressgeneration (e.g., for address generation that uses2^(scale)*index+base+displacement).

Displacement Factor Field 762B (note that the juxtaposition ofdisplacement field 762A directly over displacement factor field 762Bindicates one or the other is used)—its content is used as part ofaddress generation; it specifies a displacement factor that is to bescaled by the size of a memory access (N)—where N is the number of bytesin the memory access (e.g., for address generation that uses2^(scale)*index+base+scaled displacement). Redundant low-order bits areignored and hence, the displacement factor field's content is multipliedby the memory operands total size (N) in order to generate the finaldisplacement to be used in calculating an effective address. The valueof N is determined by the processor hardware at runtime based on thefull opcode field 774 (described later herein) and the data manipulationfield 754C. The displacement field 762A and the displacement factorfield 762B are optional in the sense that they are not used for the nomemory access 705 instruction templates and/or different embodiments mayimplement only one or none of the two.

Data element width field 764—its content distinguishes which one of anumber of data element widths is to be used (in some embodiments for allinstructions; in other embodiments for only some of the instructions).This field is optional in the sense that it is not needed if only onedata element width is supported and/or data element widths are supportedusing some aspect of the opcodes.

Write mask field 770—its content controls, on a per data elementposition basis, whether that data element position in the destinationvector operand reflects the result of the base operation andaugmentation operation. Class A instruction templates supportmerging-writemasking, while class B instruction templates support bothmerging- and zeroing-writemasking. When merging, vector masks allow anyset of elements in the destination to be protected from updates duringthe execution of any operation (specified by the base operation and theaugmentation operation); in other one embodiment, preserving the oldvalue of each element of the destination where the corresponding maskbit has a 0. In contrast, when zeroing vector masks allow any set ofelements in the destination to be zeroed during the execution of anyoperation (specified by the base operation and the augmentationoperation); in one embodiment, an element of the destination is set to 0when the corresponding mask bit has a 0 value. A subset of thisfunctionality is the ability to control the vector length of theoperation being performed (that is, the span of elements being modified,from the first to the last one); however, it is not necessary that theelements that are modified be consecutive. Thus, the write mask field770 allows for partial vector operations, including loads, stores,arithmetic, logical, etc. While embodiments of the invention aredescribed in which the write mask field's 770 content selects one of anumber of write mask registers that contains the write mask to be used(and thus the write mask field's 770 content indirectly identifies thatmasking to be performed), alternative embodiments instead or additionalallow the mask write field's 770 content to directly specify the maskingto be performed.

Immediate field 772—its content allows for the specification of animmediate. This field is optional in the sense that is it not present inan implementation of the generic vector friendly format that does notsupport immediate and it is not present in instructions that do not usean immediate.

Class field 768—its content distinguishes between different classes ofinstructions. With reference to FIGS. 7A-B, the contents of this fieldselect between class A and class B instructions. In FIGS. 7A-B, roundedcorner squares are used to indicate a specific value is present in afield (e.g., class A 768A and class B 768B for the class field 768respectively in FIGS. 7A-B).

Instruction Templates of Class A

In the case of the non-memory access 705 instruction templates of classA, the alpha field 752 is interpreted as an RS field 752A, whose contentdistinguishes which one of the different augmentation operation typesare to be performed (e.g., round 752A.1 and data transform 752A.2 arerespectively specified for the no memory access, round type operation710 and the no memory access, data transform type operation 715instruction templates), while the beta field 754 distinguishes which ofthe operations of the specified type is to be performed. In the nomemory access 705 instruction templates, the scale field 760, thedisplacement field 762A, and the displacement scale filed 762B are notpresent.

No-Memory Access Instruction Templates—Full Round Control Type Operation

In the no memory access full round control type operation 710instruction template, the beta field 754 is interpreted as a roundcontrol field 754A, whose content(s) provide static rounding. While inthe described embodiments of the invention the round control field 754Aincludes a suppress all floating point exceptions (SAE) field 756 and around operation control field 758, alternative embodiments may supportmay encode both these concepts into the same field or only have one orthe other of these concepts/fields (e.g., may have only the roundoperation control field 758).

SAE field 756—its content distinguishes whether or not to disable theexception event reporting; when the SAE field's 756 content indicatessuppression is enabled, a given instruction does not report any kind offloating-point exception flag and does not raise any floating pointexception handler.

Round operation control field 758—its content distinguishes which one ofa group of rounding operations to perform (e.g., Round-up, Round-down,Round-towards-zero and Round-to-nearest). Thus, the round operationcontrol field 758 allows for the changing of the rounding mode on a perinstruction basis. In one embodiment of the invention where a processorincludes a control register for specifying rounding modes, the roundoperation control field's 750 content overrides that register value.

No Memory Access Instruction Templates—Data Transform Type Operation

In the no memory access data transform type operation 715 instructiontemplate, the beta field 754 is interpreted as a data transform field754B, whose content distinguishes which one of a number of datatransforms is to be performed (e.g., no data transform, swizzle,broadcast).

In the case of a memory access 720 instruction template of class A, thealpha field 752 is interpreted as an eviction hint field 752B, whosecontent distinguishes which one of the eviction hints is to be used (inFIG. 7A, temporal 752B.1 and non-temporal 752B.2 are respectivelyspecified for the memory access, temporal 725 instruction template andthe memory access, non-temporal 730 instruction template), while thebeta field 754 is interpreted as a data manipulation field 754C, whosecontent distinguishes which one of a number of data manipulationoperations (also known as primitives) is to be performed (e.g., nomanipulation; broadcast; up conversion of a source; and down conversionof a destination). The memory access 720 instruction templates includethe scale field 760, and optionally the displacement field 762A or thedisplacement scale field 762B.

Vector memory instructions perform vector loads from and vector storesto memory, with conversion support. As with regular vector instructions,vector memory instructions transfer data from/to memory in a dataelement-wise fashion, with the elements that are actually transferred isdictated by the contents of the vector mask that is selected as thewrite mask.

Memory Access Instruction Templates—Temporal

Temporal data is data likely to be reused soon enough to benefit fromcaching. This is, however, a hint, and different processors mayimplement it in different ways, including ignoring the hint entirely.

Memory Access Instruction Templates—Non-Temporal

Non-temporal data is data unlikely to be reused soon enough to benefitfrom caching in the 1st-level cache and should be given priority foreviction. This is, however, a hint, and different processors mayimplement it in different ways, including ignoring the hint entirely.

Instruction Templates of Class B

In the case of the instruction templates of class B, the alpha field 752is interpreted as a write mask control (Z) field 752C, whose contentdistinguishes whether the write masking controlled by the write maskfield 770 should be a merging or a zeroing.

In the case of the non-memory access 705 instruction templates of classB, part of the beta field 754 is interpreted as an RL field 757A, whosecontent distinguishes which one of the different augmentation operationtypes are to be performed (e.g., round 757A.1 and vector length (VSIZE)757A.2 are respectively specified for the no memory access, write maskcontrol, partial round control type operation 712 instruction templateand the no memory access, write mask control, VSIZE type operation 717instruction template), while the rest of the beta field 754distinguishes which of the operations of the specified type is to beperformed. In the no memory access 705 instruction templates, the scalefield 760, the displacement field 762A, and the displacement scale filed762B are not present.

In the no memory access, write mask control, partial round control typeoperation 710 instruction template, the rest of the beta field 754 isinterpreted as a round operation field 759A and exception eventreporting is disabled (a given instruction does not report any kind offloating-point exception flag and does not raise any floating pointexception handler).

Round operation control field 759A—just as round operation control field758, its content distinguishes which one of a group of roundingoperations to perform (e.g., Round-up, Round-down, Round-towards-zeroand Round-to-nearest). Thus, the round operation control field 759Aallows for the changing of the rounding mode on a per instruction basis.In one embodiment of the invention where a processor includes a controlregister for specifying rounding modes, the round operation controlfield's 750 content overrides that register value.

In the no memory access, write mask control, VSIZE type operation 717instruction template, the rest of the beta field 754 is interpreted as avector length field 759B, whose content distinguishes which one of anumber of data vector lengths is to be performed on (e.g., 128, 256, or512 byte).

In the case of a memory access 720 instruction template of class B, partof the beta field 754 is interpreted as a broadcast field 757B, whosecontent distinguishes whether or not the broadcast type datamanipulation operation is to be performed, while the rest of the betafield 754 is interpreted the vector length field 759B. The memory access720 instruction templates include the scale field 760, and optionallythe displacement field 762A or the displacement scale field 762B.

With regard to the generic vector friendly instruction format 700, afull opcode field 774 is shown including the format field 740, the baseoperation field 742, and the data element width field 764. While oneembodiment is shown where the full opcode field 774 includes all ofthese fields, the full opcode field 774 includes less than all of thesefields in embodiments that do not support all of them. The full opcodefield 774 provides the operation code (opcode).

The augmentation operation field 750, the data element width field 764,and the write mask field 770 allow these features to be specified on aper instruction basis in the generic vector friendly instruction format.

The combination of write mask field and data element width field createtyped instructions in that they allow the mask to be applied based ondifferent data element widths.

The various instruction templates found within class A and class B arebeneficial in different situations. In some embodiments of theinvention, different processors or different cores within a processormay support only class A, only class B, or both classes. For instance, ahigh performance general purpose out-of-order core intended forgeneral-purpose computing may support only class B, a core intendedprimarily for graphics and/or scientific (throughput) computing maysupport only class A, and a core intended for both may support both (ofcourse, a core that has some mix of templates and instructions from bothclasses but not all templates and instructions from both classes iswithin the purview of the invention). Also, a single processor mayinclude multiple cores, all of which support the same class or in whichdifferent cores support different class. For instance, in a processorwith separate graphics and general purpose cores, one of the graphicscores intended primarily for graphics and/or scientific computing maysupport only class A, while one or more of the general purpose cores maybe high performance general purpose cores with out of order executionand register renaming intended for general-purpose computing thatsupport only class B. Another processor that does not have a separategraphics core, may include one more general purpose in-order orout-of-order cores that support both class A and class B. Of course,features from one class may also be implement in the other class indifferent embodiments of the invention. Programs written in a high levellanguage would be put (e.g., just in time compiled or staticallycompiled) into an variety of different executable forms, including: 1) aform having only instructions of the class(es) supported by the targetprocessor for execution; or 2) a form having alternative routineswritten using different combinations of the instructions of all classesand having control flow code that selects the routines to execute basedon the instructions supported by the processor which is currentlyexecuting the code.

Exemplary Specific Vector Friendly Instruction Format

FIGS. 8A-D is a block diagram illustrating an exemplary specific vectorfriendly instruction format according to embodiments of the invention.FIGS. 8A-D show a specific vector friendly instruction format 800 thatis specific in the sense that it specifies the location, size,interpretation, and order of the fields, as well as values for some ofthose fields. The specific vector friendly instruction format 800 may beused to extend the x86 instruction set, and thus some of the fields aresimilar or the same as those used in the existing x86 instruction setand extension thereof (e.g., AVX). This format remains consistent withthe prefix encoding field, real opcode byte field, MOD R/M field, SIBfield, displacement field, and immediate fields of the existing x86instruction set with extensions. The fields from FIG. 7 into which thefields from FIGS. 8A-D map are illustrated.

It should be understood that, although embodiments of the invention aredescribed with reference to the specific vector friendly instructionformat 800 in the context of the generic vector friendly instructionformat 700 for illustrative purposes, the invention is not limited tothe specific vector friendly instruction format 800 except whereclaimed. For example, the generic vector friendly instruction format 700contemplates a variety of possible sizes for the various fields, whilethe specific vector friendly instruction format 800 is shown as havingfields of specific sizes. By way of specific example, while the dataelement width field 764 is illustrated as a one bit field in thespecific vector friendly instruction format 800, the invention is not solimited (that is, the generic vector friendly instruction format 700contemplates other sizes of the data element width field 764).

The generic vector friendly instruction format 700 includes thefollowing fields listed below in the order illustrated in FIG. 8A.

EVEX Prefix (Bytes 0-3) 802—is encoded in a four-byte form.

Format Field 740 (EVEX Byte 0, bits [7:0])—the first byte (EVEX Byte 0)is the format field 740 and it contains 0x62 (the unique value used fordistinguishing the vector friendly instruction format in one embodimentof the invention).

The second-fourth bytes (EVEX Bytes 1-3) include a number of bit fieldsproviding specific capability.

REX field 805 (EVEX Byte 1, bits [7-5])—consists of a EVEX.R bit field(EVEX Byte 1, bit [7]—R), EVEX.X bit field (EVEX byte 1, bit [6]—X), and757BEX byte 1, bit[5]—B). The EVEX.R, EVEX.X, and EVEX.B bit fieldsprovide the same functionality as the corresponding VEX bit fields, andare encoded using 1s complement form, i.e. ZMM0 is encoded as 1111B,ZMM15 is encoded as 0000B. Other fields of the instructions encode thelower three bits of the register indexes as is known in the art (rrr,xxx, and bbb), so that Rrrr, Xxxx, and Bbbb may be formed by addingEVEX.R, EVEX.X, and EVEX.B.

REX′ field 710—this is the first part of the REX′ field 710 and is theEVEX.R′ bit field (EVEX Byte 1, bit [4]—R′) that is used to encodeeither the upper 16 or lower 16 of the extended 32 register set. In oneembodiment of the invention, this bit, along with others as indicatedbelow, is stored in bit inverted format to distinguish (in thewell-known x86 32-bit mode) from the BOUND instruction, whose realopcode byte is 62, but does not accept in the MOD R/M field (describedbelow) the value of 11 in the MOD field; alternative embodiments of theinvention do not store this and the other indicated bits below in theinverted format. A value of 1 is used to encode the lower 16 registers.In other words, R′Rrrr is formed by combining EVEX.R′, EVEX.R, and theother RRR from other fields.

Opcode map field 815 (EVEX byte 1, bits [3:0]—mmmm)—its content encodesan implied leading opcode byte (0F, 0F 38, or 0F 3).

Data element width field 764 (EVEX byte 2, bit [7]—W)—is represented bythe notation EVEX.W. EVEX.W is used to define the granularity (size) ofthe datatype (either 32-bit data elements or 64-bit data elements).

EVEX.vvvv 820 (EVEX Byte 2, bits [6:3]—vvvv)—the role of EVEX.vvvv mayinclude the following: 1) EVEX.vvvv encodes the first source registeroperand, specified in inverted (1s complement) form and is valid forinstructions with 2 or more source operands; 2) EVEX.vvvv encodes thedestination register operand, specified in 1s complement form forcertain vector shifts; or 3) EVEX.vvvv does not encode any operand, thefield is reserved and should contain 1111b. Thus, EVEX.vvvv field 820encodes the 4 low-order bits of the first source register specifierstored in inverted (1s complement) form. Depending on the instruction,an extra different EVEX bit field is used to extend the specifier sizeto 32 registers.

EVEX.U 768 Class field (EVEX byte 2, bit [2]—U)—If EVEX.U=0, itindicates class A or EVEX.U0; if EVEX.U=1, it indicates class B orEVEX.U1.

Prefix encoding field 825 (EVEX byte 2, bits [1:0]—pp)—providesadditional bits for the base operation field. In addition to providingsupport for the legacy SSE instructions in the EVEX prefix format, thisalso has the benefit of compacting the SIMD prefix (rather thanrequiring a byte to express the SIMD prefix, the EVEX prefix requiresonly 2 bits). In one embodiment, to support legacy SSE instructions thatuse a SIMD prefix (66H, F2H, F3H) in both the legacy format and in theEVEX prefix format, these legacy SIMD prefixes are encoded into the SIMDprefix encoding field; and at runtime are expanded into the legacy SIMDprefix prior to being provided to the decoder's PLA (so the PLA canexecute both the legacy and EVEX format of these legacy instructionswithout modification). Although newer instructions could use the EVEXprefix encoding field's content directly as an opcode extension, certainembodiments expand in a similar fashion for consistency but allow fordifferent meanings to be specified by these legacy SIMD prefixes. Analternative embodiment may redesign the PLA to support the 2 bit SIMDprefix encodings, and thus not require the expansion.

Alpha field 752 (EVEX byte 3, bit [7]—EH; also known as EVEX.EH,EVEX.rs, EVEX.RL, EVEX.write mask control, and EVEX.N; also illustratedwith α)—as previously described, this field is context specific.

Beta field 754 (EVEX byte 3, bits [6:4]—SSS, also known as EVEX.s₂₋₀,EVEX.r₂₋₀, EVEX.rr1, EVEX.LL0, EVEX.LLB; also illustrated with βββ)—aspreviously described, this field is context specific.

REX′ field 710—this is the remainder of the REX′ field and is theEVEX.V′ bit field (EVEX Byte 3, bit [3]—V′) that may be used to encodeeither the upper 16 or lower 16 of the extended 32 register set. Thisbit is stored in bit inverted format. A value of 1 is used to encode thelower 16 registers. In other words, V′VVVV is formed by combiningEVEX.V′, EVEX.vvvv.

Write mask field 770 (EVEX byte 3, bits [2:0]—kkk)—its content specifiesthe index of a register in the write mask registers as previouslydescribed. In one embodiment of the invention, the specific valueEVEX.kkk=000 has a special behavior implying no write mask is used forthe particular instruction (this may be implemented in a variety of waysincluding the use of a write mask hardwired to all ones or hardware thatbypasses the masking hardware).

Real Opcode Field 830 (Byte 4) is also known as the opcode byte. Part ofthe opcode is specified in this field.

MOD R/M Field 840 (Byte 5) includes MOD field 842, Reg field 844, andR/M field 846. As previously described, the MOD field's 842 contentdistinguishes between memory access and non-memory access operations.The role of Reg field 844 can be summarized to two situations: encodingeither the destination register operand or a source register operand, orbe treated as an opcode extension and not used to encode any instructionoperand. The role of R/M field 846 may include the following: encodingthe instruction operand that references a memory address, or encodingeither the destination register operand or a source register operand.

Scale, Index, Base (SIB) Byte (Byte 6) 850—As previously described, thescale field's 752 content is used for memory address generation. SIB.xxx854 and SIB.bbb 856—the contents of these fields have been previouslyreferred to with regard to the register indexes Xxxx and Bbbb.

Displacement field 762A (Bytes 7-10)—when MOD field 842 contains 10,bytes 7-10 are the displacement field 762A, and it works the same as thelegacy 32-bit displacement (disp32) and works at byte granularity.

Displacement factor field 762B (Byte 7)—when MOD field 842 contains 01,byte 7 is the displacement factor field 762B. The location of this fieldis that same as that of the legacy x86 instruction set 8-bitdisplacement (disp8), which works at byte granularity. Since disp8 issign extended, it can only address between −128 and 127 bytes offsets;in terms of 64 byte cache lines, disp8 uses 8 bits that can be set toonly four really useful values −128, −64, 0, and 64; since a greaterrange is often needed, disp32 is used; however, disp32 requires 4 bytes.In contrast to disp8 and disp32, the displacement factor field 762B is areinterpretation of disp8; when using displacement factor field 762B,the actual displacement is determined by the content of the displacementfactor field multiplied by the size of the memory operand access (N).This type of displacement is referred to as disp8*N. This reduces theaverage instruction length (a single byte of used for the displacementbut with a much greater range). Such compressed displacement is based onthe assumption that the effective displacement is multiple of thegranularity of the memory access, and hence, the redundant low-orderbits of the address offset do not need to be encoded. In other words,the displacement factor field 762B substitutes the legacy x86instruction set 8-bit displacement. Thus, the displacement factor field762B is encoded the same way as an x86 instruction set 8-bitdisplacement (so no changes in the ModRM/SIB encoding rules) with theonly exception that disp8 is overloaded to disp8*N. In other words,there are no changes in the encoding rules or encoding lengths but onlyin the interpretation of the displacement value by hardware (which needsto scale the displacement by the size of the memory operand to obtain abyte-wise address offset). Immediate field 772 operates as previouslydescribed.

Full Opcode Field

FIG. 8B is a block diagram illustrating the fields of the specificvector friendly instruction format 800 that make up the full opcodefield 774 according to one embodiment of the invention. Specifically,the full opcode field 774 includes the format field 740, the baseoperation field 742, and the data element width (W) field 764. The baseoperation field 742 includes the prefix encoding field 825, the opcodemap field 815, and the real opcode field 830.

Register Index Field

FIG. 8C is a block diagram illustrating the fields of the specificvector friendly instruction format 800 that make up the register indexfield 744 according to one embodiment of the invention. Specifically,the register index field 744 includes the REX field 805, the REX′ field810, the MODR/M.reg field 844, the MODR/M.r/m field 846, the VVVV field820, xxx field 854, and the bbb field 856.

Augmentation Operation Field

FIG. 8D is a block diagram illustrating the fields of the specificvector friendly instruction format 800 that make up the augmentationoperation field 750 according to one embodiment of the invention. Whenthe class (U) field 768 contains 0, it signifies EVEX.U0 (class A 768A);when it contains 1, it signifies EVEX.U1 (class B 768B). When U=0 andthe MOD field 842 contains 11 (signifying a no memory access operation),the alpha field 752 (EVEX byte 3, bit [7]—EH) is interpreted as the rsfield 752A. When the rs field 752A contains a 1 (round 752A.1), the betafield 754 (EVEX byte 3, bits [6:4]—SSS) is interpreted as the roundcontrol field 754A. The round control field 754A includes a one bit SAEfield 756 and a two bit round operation field 758. When the rs field752A contains a 0 (data transform 752A.2), the beta field 754 (EVEX byte3, bits [6:4]—SSS) is interpreted as a three bit data transform field754B. When U=0 and the MOD field 842 contains 00, 01, or 10 (signifyinga memory access operation), the alpha field 752 (EVEX byte 3, bit[7]—EH) is interpreted as the eviction hint (EH) field 752B and the betafield 754 (EVEX byte 3, bits [6:4]—SSS) is interpreted as a three bitdata manipulation field 754C.

When U=1, the alpha field 752 (EVEX byte 3, bit [7]—EH) is interpretedas the write mask control (Z) field 752C. When U=1 and the MOD field 842contains 11 (signifying a no memory access operation), part of the betafield 754 (EVEX byte 3, bit [4]—S₀) is interpreted as the RL field 757A;when it contains a 1 (round 757A.1) the rest of the beta field 754 (EVEXbyte 3, bit [6-5]—S₂₋₁) is interpreted as the round operation field759A, while when the RL field 757A contains a 0 (VSIZE 757.A2) the restof the beta field 754 (EVEX byte 3, bit [6-5]—S₂₋₁) is interpreted asthe vector length field 759B (EVEX byte 3, bit [6-5]—L₁₋₀). When U=1 andthe MOD field 842 contains 00, 01, or 10 (signifying a memory accessoperation), the beta field 754 (EVEX byte 3, bits [6:4]—SSS) isinterpreted as the vector length field 759B (EVEX byte 3, bit[6-5]—L₁₋₀) and the broadcast field 757B (EVEX byte 3, bit [4]—B).

Exemplary Register Architecture

FIG. 9 is a block diagram of a register architecture 900 according toone embodiment of the invention. In the embodiment illustrated, thereare 32 vector registers 910 that are 512 bits wide; these registers arereferenced as zmm0 through zmm31. The lower order 256 bits of the lower16 zmm registers are overlaid on registers ymm0-16. The lower order 128bits of the lower 16 zmm registers (the lower order 128 bits of the ymmregisters) are overlaid on registers xmm0-15. The specific vectorfriendly instruction format 800 operates on these overlaid register fileas illustrated in the below tables.

Adjustable Opera- Vector Length Class tions Registers InstructionTemplates A (FIG. 710, 715, zmm registers (the that do not include 7A; U= 0) 725, 730 vector length is 64 byte) the vector length field B (FIG.712 zmm registers (the 759B 7B; U = 1) vector length is 64 byte)Instruction templates B (FIG. 717, 727 zmm, ymm, or xmm that do includethe 7B; U = 1) registers (the vector vector length field length is 64byte, 32 759B byte, or 16 byte) depending on the vector length field759B

In other words, the vector length field 759B selects between a maximumlength and one or more other shorter lengths, where each such shorterlength is half the length of the preceding length; and instructionstemplates without the vector length field 759B operate on the maximumvector length. Further, in one embodiment, the class B instructiontemplates of the specific vector friendly instruction format 800 operateon packed or scalar single/double-precision floating point data andpacked or scalar integer data. Scalar operations are operationsperformed on the lowest order data element position in an zmm/ymm/xmmregister; the higher order data element positions are either left thesame as they were prior to the instruction or zeroed depending on theembodiment.

Write mask registers 915—in the embodiment illustrated, there are 8write mask registers (k0 through k7), each 64 bits in size. In analternate embodiment, the write mask registers 915 are 16 bits in size.As previously described, in one embodiment of the invention, the vectormask register k0 cannot be used as a write mask; when the encoding thatwould normally indicate k0 is used for a write mask, it selects ahardwired write mask of 0xFFFF, effectively disabling write masking forthat instruction.

General-purpose registers 925—in the embodiment illustrated, there aresixteen 64-bit general-purpose registers that are used along with theexisting x86 addressing modes to address memory operands. Theseregisters are referenced by the names RAX, RBX, RCX, RDX, RBP, RSI, RDI,RSP, and R8 through R15.

Scalar floating point stack register file (x87 stack) 945, on which isaliased the MMX packed integer flat register file 950—in the embodimentillustrated, the x87 stack is an eight-element stack used to performscalar floating-point operations on 32/64/80-bit floating point datausing the x87 instruction set extension; while the MMX registers areused to perform operations on 64-bit packed integer data, as well as tohold operands for some operations performed between the MMX and XMMregisters.

Alternative embodiments of the invention may use wider or narrowerregisters. Additionally, alternative embodiments of the invention mayuse more, less, or different register files and registers.

Exemplary Core Architectures, Processors, and Computer Architectures

Processor cores may be implemented in different ways, for differentpurposes, and in different processors. For instance, implementations ofsuch cores may include: 1) a general purpose in-order core intended forgeneral-purpose computing; 2) a high performance general purposeout-of-order core intended for general-purpose computing; 3) a specialpurpose core intended primarily for graphics and/or scientific(throughput) computing. Implementations of different processors mayinclude: 1) a CPU including one or more general purpose in-order coresintended for general-purpose computing and/or one or more generalpurpose out-of-order cores intended for general-purpose computing; and2) a coprocessor including one or more special purpose cores intendedprimarily for graphics and/or scientific (throughput). Such differentprocessors lead to different computer system architectures, which mayinclude: 1) the coprocessor on a separate chip from the CPU; 2) thecoprocessor on a separate die in the same package as a CPU; 3) thecoprocessor on the same die as a CPU (in which case, such a coprocessoris sometimes referred to as special purpose logic, such as integratedgraphics and/or scientific (throughput) logic, or as special purposecores); and 4) a system on a chip that may include on the same die thedescribed CPU (sometimes referred to as the application core(s) orapplication processor(s)), the above described coprocessor, andadditional functionality. Exemplary core architectures are describednext, followed by descriptions of exemplary processors and computerarchitectures.

Exemplary Core Architectures

In-Order and Out-of-Order Core Block Diagram

FIG. 10A is a block diagram illustrating both an exemplary in-orderpipeline and an exemplary register renaming, out-of-orderissue/execution pipeline according to embodiments of the invention. FIG.10B is a block diagram illustrating both an exemplary embodiment of anin-order architecture core and an exemplary register renaming,out-of-order issue/execution architecture core to be included in aprocessor according to embodiments of the invention. The solid linedboxes in FIGS. 10A-B illustrate the in-order pipeline and in-order core,while the optional addition of the dashed lined boxes illustrates theregister renaming, out-of-order issue/execution pipeline and core. Giventhat the in-order aspect is a subset of the out-of-order aspect, theout-of-order aspect will be described.

In FIG. 10A, a processor pipeline 1000 includes a fetch stage 1002, alength decode stage 1004, a decode stage 1006, an allocation stage 1008,a renaming stage 1010, a scheduling (also known as a dispatch or issue)stage 1012, a register read/memory read stage 1014, an execute stage1016, a write back/memory write stage 1018, an exception handling stage1022, and a commit stage 1024.

FIG. 10B shows processor core 1090 including a front end unit 1030coupled to an execution engine unit 1050, and both are coupled to amemory unit 1070. The core 1090 may be a reduced instruction setcomputing (RISC) core, a complex instruction set computing (CISC) core,a very long instruction word (VLIW) core, or a hybrid or alternativecore type. As yet another option, the core 1090 may be a special-purposecore, such as, for example, a network or communication core, compressionengine, coprocessor core, general purpose computing graphics processingunit (GPGPU) core, graphics core, or the like.

The front end unit 1030 includes a branch prediction unit 1032 coupledto an instruction cache unit 1034, which is coupled to an instructiontranslation lookaside buffer (TLB) 1036, which is coupled to aninstruction fetch unit 1038, which is coupled to a decode unit 1040. Thedecode unit 1040 (or decoder) may decode instructions, and generate asan output one or more micro-operations, micro-code entry points,microinstructions, other instructions, or other control signals, whichare decoded from, or which otherwise reflect, or are derived from, theoriginal instructions. The decode unit 1040 may be implemented usingvarious different mechanisms. Examples of suitable mechanisms include,but are not limited to, look-up tables, hardware implementations,programmable logic arrays (PLAs), microcode read only memories (ROMs),etc. In one embodiment, the core 1090 includes a microcode ROM or othermedium that stores microcode for certain macroinstructions (e.g., indecode unit 1040 or otherwise within the front end unit 1030). Thedecode unit 1040 is coupled to a rename/allocator unit 1052 in theexecution engine unit 1050.

The execution engine unit 1050 includes the rename/allocator unit 1052coupled to a retirement unit 1054 and a set of one or more schedulerunit(s) 1056. The scheduler unit(s) 1056 represents any number ofdifferent schedulers, including reservations stations, centralinstruction window, etc. The scheduler unit(s) 1056 is coupled to thephysical register file(s) unit(s) 1058. Each of the physical registerfile(s) units 1058 represents one or more physical register files,different ones of which store one or more different data types, such asscalar integer, scalar floating point, packed integer, packed floatingpoint, vector integer, vector floating point, status (e.g., aninstruction pointer that is the address of the next instruction to beexecuted), etc. In one embodiment, the physical register file(s) unit1058 comprises a vector registers unit, a write mask registers unit, anda scalar registers unit. These register units may provide architecturalvector registers, vector mask registers, and general purpose registers.The physical register file(s) unit(s) 1058 is overlapped by theretirement unit 1054 to illustrate various ways in which registerrenaming and out-of-order execution may be implemented (e.g., using areorder buffer(s) and a retirement register file(s); using a futurefile(s), a history buffer(s), and a retirement register file(s); using aregister maps and a pool of registers; etc.). The retirement unit 1054and the physical register file(s) unit(s) 1058 are coupled to theexecution cluster(s) 1060. The execution cluster(s) 1060 includes a setof one or more execution units 1062 and a set of one or more memoryaccess units 1064. The execution units 1062 may perform variousoperations (e.g., shifts, addition, subtraction, multiplication) and onvarious types of data (e.g., scalar floating point, packed integer,packed floating point, vector integer, vector floating point). Whilesome embodiments may include a number of execution units dedicated tospecific functions or sets of functions, other embodiments may includeonly one execution unit or multiple execution units that all perform allfunctions. The scheduler unit(s) 1056, physical register file(s) unit(s)1058, and execution cluster(s) 1060 are shown as being possibly pluralbecause certain embodiments create separate pipelines for certain typesof data/operations (e.g., a scalar integer pipeline, a scalar floatingpoint/packed integer/packed floating point/vector integer/vectorfloating point pipeline, and/or a memory access pipeline that each havetheir own scheduler unit, physical register file(s) unit, and/orexecution cluster—and in the case of a separate memory access pipeline,certain embodiments are implemented in which only the execution clusterof this pipeline has the memory access unit(s) 1064). It should also beunderstood that where separate pipelines are used, one or more of thesepipelines may be out-of-order issue/execution and the rest in-order.

The set of memory access units 1064 is coupled to the memory unit 1070,which includes a data TLB unit 1072 coupled to a data cache unit 1074coupled to a level 2 (L2) cache unit 1076. In one exemplary embodiment,the memory access units 1064 may include a load unit, a store addressunit, and a store data unit, each of which is coupled to the data TLBunit 1072 in the memory unit 1070. The instruction cache unit 1034 isfurther coupled to a level 2 (L2) cache unit 1076 in the memory unit1070. The L2 cache unit 1076 is coupled to one or more other levels ofcache and eventually to a main memory.

By way of example, the exemplary register renaming, out-of-orderissue/execution core architecture may implement the pipeline 1000 asfollows: 1) the instruction fetch 1038 performs the fetch and lengthdecoding stages 1002 and 1004; 2) the decode unit 1040 performs thedecode stage 1006; 3) the rename/allocator unit 1052 performs theallocation stage 1008 and renaming stage 1010; 4) the scheduler unit(s)1056 performs the schedule stage 1012; 5) the physical register file(s)unit(s) 1058 and the memory unit 1070 perform the register read/memoryread stage 1014; the execution cluster 1060 perform the execute stage1016; 6) the memory unit 1070 and the physical register file(s) unit(s)1058 perform the write back/memory write stage 1018; 7) various unitsmay be involved in the exception handling stage 1022; and 8) theretirement unit 1054 and the physical register file(s) unit(s) 1058perform the commit stage 1024.

The core 1090 may support one or more instructions sets (e.g., the x86instruction set (with some extensions that have been added with newerversions); the MIPS instruction set of MIPS Technologies of Sunnyvale,Calif.; the ARM instruction set (with optional additional extensionssuch as NEON) of ARM Holdings of Sunnyvale, Calif.), including theinstruction(s) described herein. In one embodiment, the core 1090includes logic to support a packed data instruction set extension (e.g.,AVX1, AVX2), thereby allowing the operations used by many multimediaapplications to be performed using packed data.

It should be understood that the core may support multithreading(executing two or more parallel sets of operations or threads), and maydo so in a variety of ways including time sliced multithreading,simultaneous multithreading (where a single physical core provides alogical core for each of the threads that physical core issimultaneously multithreading), or a combination thereof (e.g., timesliced fetching and decoding and simultaneous multithreading thereaftersuch as in the Intel® Hyperthreading technology).

While register renaming is described in the context of out-of-orderexecution, it should be understood that register renaming may be used inan in-order architecture. While the illustrated embodiment of theprocessor also includes separate instruction and data cache units1034/1074 and a shared L2 cache unit 1076, alternative embodiments mayhave a single internal cache for both instructions and data, such as,for example, a Level 1 (L1) internal cache, or multiple levels ofinternal cache. In some embodiments, the system may include acombination of an internal cache and an external cache that is externalto the core and/or the processor. Alternatively, all of the cache may beexternal to the core and/or the processor.

Specific Exemplary In-Order Core Architecture

FIGS. 11A-B illustrate a block diagram of a more specific exemplaryin-order core architecture, which core would be one of several logicblocks (including other cores of the same type and/or different types)in a chip. The logic blocks communicate through a high-bandwidthinterconnect network (e.g., a ring network) with some fixed functionlogic, memory I/O interfaces, and other necessary I/O logic, dependingon the application.

FIG. 11A is a block diagram of a single processor core, along with itsconnection to the on-die interconnect network 1102 and with its localsubset of the Level 2 (L2) cache 1104, according to embodiments of theinvention. In one embodiment, an instruction decoder 1100 supports thex86 instruction set with a packed data instruction set extension. An L1cache 1106 allows low-latency accesses to cache memory into the scalarand vector units. While in one embodiment (to simplify the design), ascalar unit 1108 and a vector unit 1110 use separate register sets(respectively, scalar registers 1112 and vector registers 1114) and datatransferred between them is written to memory and then read back in froma level 1 (L1) cache 1106, alternative embodiments of the invention mayuse a different approach (e.g., use a single register set or include acommunication path that allow data to be transferred between the tworegister files without being written and read back).

The local subset of the L2 cache 1104 is part of a global L2 cache thatis divided into separate local subsets, one per processor core. Eachprocessor core has a direct access path to its own local subset of theL2 cache 1104. Data read by a processor core is stored in its L2 cachesubset 1104 and can be accessed quickly, in parallel with otherprocessor cores accessing their own local L2 cache subsets. Data writtenby a processor core is stored in its own L2 cache subset 1104 and isflushed from other subsets, if necessary. The ring network ensurescoherency for shared data. The ring network is bi-directional to allowagents such as processor cores, L2 caches and other logic blocks tocommunicate with each other within the chip. Each ring data-path is1012-bits wide per direction.

FIG. 11B is an expanded view of part of the processor core in FIG. 11Aaccording to embodiments of the invention. FIG. 11B includes an L1 datacache 1106A part of the L1 cache 1104, as well as more detail regardingthe vector unit 1110 and the vector registers 1114. Specifically, thevector unit 1110 is a 16-wide vector processing unit (VPU) (see the16-wide ALU 1128), which executes one or more of integer,single-precision float, and double-precision float instructions. The VPUsupports swizzling the register inputs with swizzle unit 1120, numericconversion with numeric convert units 1122A-B, and replication withreplication unit 1124 on the memory input. Write mask registers 1126allow predicating resulting vector writes.

FIG. 12 is a block diagram of a processor 1200 that may have more thanone core, may have an integrated memory controller, and may haveintegrated graphics according to embodiments of the invention. The solidlined boxes in FIG. 12 illustrate a processor 1200 with a single core1202A, a system agent 1210, a set of one or more bus controller units1216, while the optional addition of the dashed lined boxes illustratesan alternative processor 1200 with multiple cores 1202A-N, a set of oneor more integrated memory controller unit(s) 1214 in the system agentunit 1210, and special purpose logic 1208.

Thus, different implementations of the processor 1200 may include: 1) aCPU with the special purpose logic 1208 being integrated graphics and/orscientific (throughput) logic (which may include one or more cores), andthe cores 1202A-N being one or more general purpose cores (e.g., generalpurpose in-order cores, general purpose out-of-order cores, acombination of the two); 2) a coprocessor with the cores 1202A-N being alarge number of special purpose cores intended primarily for graphicsand/or scientific (throughput); and 3) a coprocessor with the cores1202A-N being a large number of general purpose in-order cores. Thus,the processor 1200 may be a general-purpose processor, coprocessor orspecial-purpose processor, such as, for example, a network orcommunication processor, compression engine, graphics processor, GPGPU(general purpose graphics processing unit), a high-throughput manyintegrated core (MIC) coprocessor (including 30 or more cores), embeddedprocessor, or the like. The processor may be implemented on one or morechips. The processor 1200 may be a part of and/or may be implemented onone or more substrates using any of a number of process technologies,such as, for example, BiCMOS, CMOS, or NMOS.

The memory hierarchy includes one or more levels of cache 1204A-N withinthe cores, a set or one or more shared cache units 1206, and externalmemory (not shown) coupled to the set of integrated memory controllerunits 1214. The set of shared cache units 1206 may include one or moremid-level caches, such as level 2 (L2), level 3 (L3), level 4 (L4), orother levels of cache, a last level cache (LLC), and/or combinationsthereof. While in one embodiment a ring based interconnect unit 1212interconnects the integrated graphics logic 1208, the set of sharedcache units 1206, and the system agent unit 1210/integrated memorycontroller unit(s) 1214, alternative embodiments may use any number ofwell-known techniques for interconnecting such units. In one embodiment,coherency is maintained between one or more cache units 1206 and cores1202-A-N.

In some embodiments, one or more of the cores 1202A-N are capable ofmultithreading. The system agent 1210 includes those componentscoordinating and operating cores 1202A-N. The system agent unit 1210 mayinclude for example a power control unit (PCU) and a display unit. ThePCU may be or include logic and components needed for regulating thepower state of the cores 1202A-N and the integrated graphics logic 1208.The display unit is for driving one or more externally connecteddisplays.

The cores 1202A-N may be homogenous or heterogeneous in terms ofarchitecture instruction set; that is, two or more of the cores 1202A-Nmay be capable of execution the same instruction set, while others maybe capable of executing only a subset of that instruction set or adifferent instruction set.

Exemplary Computer Architectures

FIGS. 13-16 are block diagrams of exemplary computer architectures.Other system designs and configurations known in the arts for laptops,desktops, handheld PCs, personal digital assistants, engineeringworkstations, servers, network devices, network hubs, switches, embeddedprocessors, digital signal processors (DSPs), graphics devices, videogame devices, set-top boxes, micro controllers, cell phones, portablemedia players, hand held devices, and various other electronic devices,are also suitable. In general, a huge variety of systems or electronicdevices capable of incorporating a processor and/or other executionlogic as disclosed herein are generally suitable.

Referring now to FIG. 13, shown is a block diagram of a system 1300 inaccordance with one embodiment of the present invention. The system 1300may include one or more processors 1310, 1315, which are coupled to acontroller hub 1320. In one embodiment the controller hub 1320 includesa graphics memory controller hub (GMCH) 1390 and an Input/Output Hub(IOH) 1350 (which may be on separate chips); the GMCH 1390 includesmemory and graphics controllers to which are coupled memory 1340 and acoprocessor 1345; the IOH 1350 is couples input/output (I/O) devices1360 to the GMCH 1390. Alternatively, one or both of the memory andgraphics controllers are integrated within the processor (as describedherein), the memory 1340 and the coprocessor 1345 are coupled directlyto the processor 1310, and the controller hub 1320 in a single chip withthe IOH 1350.

The optional nature of additional processors 1315 is denoted in FIG. 13with broken lines. Each processor 1310, 1315 may include one or more ofthe processing cores described herein and may be some version of theprocessor 1200.

The memory 1340 may be, for example, dynamic random access memory(DRAM), phase change memory (PCM), or a combination of the two. For atleast one embodiment, the controller hub 1320 communicates with theprocessor(s) 1310, 1315 via a multi-drop bus, such as a frontside bus(FSB), point-to-point interface such as QuickPath Interconnect (QPI), orsimilar connection 1395.

In one embodiment, the coprocessor 1345 is a special-purpose processor,such as, for example, a high-throughput MIC processor, a network orcommunication processor, compression engine, graphics processor, GPGPU,embedded processor, or the like. In one embodiment, controller hub 1320may include an integrated graphics accelerator.

There can be a variety of differences between the physical resources1310, 1315 in terms of a spectrum of metrics of merit includingarchitectural, microarchitectural, thermal, power consumptioncharacteristics, and the like.

In one embodiment, the processor 1310 executes instructions that controldata processing operations of a general type. Embedded within theinstructions may be coprocessor instructions. The processor 1310recognizes these coprocessor instructions as being of a type that shouldbe executed by the attached coprocessor 1345. Accordingly, the processor1310 issues these coprocessor instructions (or control signalsrepresenting coprocessor instructions) on a coprocessor bus or otherinterconnect, to coprocessor 1345. Coprocessor(s) 1345 accept andexecute the received coprocessor instructions.

Referring now to FIG. 14, shown is a block diagram of a first morespecific exemplary system 1400 in accordance with an embodiment of thepresent invention. As shown in FIG. 14, multiprocessor system 1400 is apoint-to-point interconnect system, and includes a first processor 1470and a second processor 1480 coupled via a point-to-point interconnect1450. Each of processors 1470 and 1480 may be some version of theprocessor 1200. In one embodiment of the invention, processors 1470 and1480 are respectively processors 1310 and 1315, while coprocessor 1438is coprocessor 1345. In another embodiment, processors 1470 and 1480 arerespectively processor 1310 coprocessor 1345.

Processors 1470 and 1480 are shown including integrated memorycontroller (IMC) units 1472 and 1482, respectively. Processor 1470 alsoincludes as part of its bus controller units point-to-point (P-P)interfaces 1476 and 1478; similarly, second processor 1480 includes P-Pinterfaces 1486 and 1488. Processors 1470, 1480 may exchange informationvia a point-to-point (P-P) interface 1450 using P-P interface circuits1478, 1488. As shown in FIG. 14, IMCs 1472 and 1482 couple theprocessors to respective memories, namely a memory 1432 and a memory1434, which may be portions of main memory locally attached to therespective processors.

Processors 1470, 1480 may each exchange information with a chipset 1490via individual P-P interfaces 1452, 1454 using point to point interfacecircuits 1476, 1494, 1486, 1498. Chipset 1490 may optionally exchangeinformation with the coprocessor 1438 via a high-performance interface1492. In one embodiment, the coprocessor 1438 is a special-purposeprocessor, such as, for example, a high-throughput MIC processor, anetwork or communication processor, compression engine, graphicsprocessor, GPGPU, embedded processor, or the like.

A shared cache (not shown) may be included in either processor oroutside of both processors, yet connected with the processors via P-Pinterconnect, such that either or both processors' local cacheinformation may be stored in the shared cache if a processor is placedinto a low power mode.

Chipset 1490 may be coupled to a first bus 1416 via an interface 1496.In one embodiment, first bus 1416 may be a Peripheral ComponentInterconnect (PCI) bus, or a bus such as a PCI Express bus or anotherthird generation I/O interconnect bus, although the scope of the presentinvention is not so limited.

As shown in FIG. 14, various I/O devices 1414 may be coupled to firstbus 1416, along with a bus bridge 1418 which couples first bus 1416 to asecond bus 1420. In one embodiment, one or more additional processor(s)1415, such as coprocessors, high-throughput MIC processors, GPGPU's,accelerators (such as, e.g., graphics accelerators or digital signalprocessing (DSP) units), field programmable gate arrays, or any otherprocessor, are coupled to first bus 1416. In one embodiment, second bus1420 may be a low pin count (LPC) bus. Various devices may be coupled toa second bus 1420 including, for example, a keyboard and/or mouse 1422,communication devices 1427 and a storage unit 1428 such as a disk driveor other mass storage device which may include instructions/code anddata 1430, in one embodiment. Further, an audio I/O 1424 may be coupledto the second bus 1420. Note that other architectures are possible. Forexample, instead of the point-to-point architecture of FIG. 14, a systemmay implement a multi-drop bus or other such architecture.

Referring now to FIG. 15, shown is a block diagram of a second morespecific exemplary system 1500 in accordance with an embodiment of thepresent invention. Like elements in FIGS. 14 and 15 bear like referencenumerals, and certain aspects of FIG. 14 have been omitted from FIG. 15in order to avoid obscuring other aspects of FIG. 15.

FIG. 15 illustrates that the processors 1470, 1480 may includeintegrated memory and I/O control logic (“CL”) 1472 and 1482,respectively. Thus, the CL 1472, 1482 include integrated memorycontroller units and include I/O control logic. FIG. 15 illustrates thatnot only are the memories 1432, 1434 coupled to the CL 1472, 1482, butalso that I/O devices 1514 are also coupled to the control logic 1472,1482. Legacy I/O devices 1515 are coupled to the chipset 1490.

Referring now to FIG. 16, shown is a block diagram of a SoC 1600 inaccordance with an embodiment of the present invention. Similar elementsin FIG. 12 bear like reference numerals. Also, dashed lined boxes areoptional features on more advanced SoCs. In FIG. 16, an interconnectunit(s) 1602 is coupled to: an application processor 1610 which includesa set of one or more cores 1202A-N, cache 1204A-N, and shared cacheunit(s) 1206; a system agent unit 1210; a bus controller unit(s) 1216;an integrated memory controller unit(s) 1214; a set or one or morecoprocessors 1620 which may include integrated graphics logic, an imageprocessor, an audio processor, and a video processor; an static randomaccess memory (SRAM) unit 1630; a direct memory access (DMA) unit 1632;and a display unit 1640 for coupling to one or more external displays.In one embodiment, the coprocessor(s) 1620 include a special-purposeprocessor, such as, for example, a network or communication processor,compression engine, GPGPU, a high-throughput MIC processor, embeddedprocessor, or the like.

Embodiments of the mechanisms disclosed herein may be implemented inhardware, software, firmware, or a combination of such implementationapproaches. Embodiments of the invention may be implemented as computerprograms or program code executing on programmable systems comprising atleast one processor, a storage system (including volatile andnon-volatile memory and/or storage elements), at least one input device,and at least one output device.

Program code, such as code 1430 illustrated in FIG. 14, may be appliedto input instructions to perform the functions described herein andgenerate output information. The output information may be applied toone or more output devices, in known fashion. For purposes of thisapplication, a processing system includes any system that has aprocessor, such as, for example; a digital signal processor (DSP), amicrocontroller, an application specific integrated circuit (ASIC), or amicroprocessor.

The program code may be implemented in a high level procedural or objectoriented programming language to communicate with a processing system.The program code may also be implemented in assembly or machinelanguage, if desired. In fact, the mechanisms described herein are notlimited in scope to any particular programming language. In any case,the language may be a compiled or interpreted language.

One or more aspects of at least one embodiment may be implemented byrepresentative instructions stored on a machine-readable medium whichrepresents various logic within the processor, which when read by amachine causes the machine to fabricate logic to perform the techniquesdescribed herein. Such representations, known as “IP cores” may bestored on a tangible, machine readable medium and supplied to variouscustomers or manufacturing facilities to load into the fabricationmachines that actually make the logic or processor.

Such machine-readable storage media may include, without limitation,non-transitory, tangible arrangements of articles manufactured or formedby a machine or device, including storage media such as hard disks, anyother type of disk including floppy disks, optical disks, compact diskread-only memories (CD-ROMs), compact disk rewritable's (CD-RWs), andmagneto-optical disks, semiconductor devices such as read-only memories(ROMs), random access memories (RAMS) such as dynamic random accessmemories (DRAMs), static random access memories (SRAMs), erasableprogrammable read-only memories (EPROMs), flash memories, electricallyerasable programmable read-only memories (EEPROMs), phase change memory(PCM), magnetic or optical cards, or any other type of media suitablefor storing electronic instructions.

Accordingly, embodiments of the invention also include non-transitory,tangible machine-readable media containing instructions or containingdesign data, such as Hardware Description Language (HDL), which definesstructures, circuits, apparatuses, processors and/or system featuresdescribed herein. Such embodiments may also be referred to as programproducts.

Emulation (Including Binary Translation, Code Morphing, etc.)

In some cases, an instruction converter may be used to convert aninstruction from a source instruction set to a target instruction set.For example, the instruction converter may translate (e.g., using staticbinary translation, dynamic binary translation including dynamiccompilation), morph, emulate, or otherwise convert an instruction to oneor more other instructions to be processed by the core. The instructionconverter may be implemented in software, hardware, firmware, or acombination thereof. The instruction converter may be on processor, offprocessor, or part on and part off processor.

FIG. 17 is a block diagram contrasting the use of a software instructionconverter to convert binary instructions in a source instruction set tobinary instructions in a target instruction set according to embodimentsof the invention. In the illustrated embodiment, the instructionconverter is a software instruction converter, although alternativelythe instruction converter may be implemented in software, firmware,hardware, or various combinations thereof. FIG. 17 shows a program in ahigh level language 1702 may be compiled using an x86 compiler 1704 togenerate x86 binary code 1706 that may be natively executed by aprocessor with at least one x86 instruction set core 1716. The processorwith at least one x86 instruction set core 1716 represents any processorthat can perform substantially the same functions as an Intel processorwith at least one x86 instruction set core by compatibly executing orotherwise processing (1) a substantial portion of the instruction set ofthe Intel x86 instruction set core or (2) object code versions ofapplications or other software targeted to run on an Intel processorwith at least one x86 instruction set core, in order to achievesubstantially the same result as an Intel processor with at least onex86 instruction set core. The x86 compiler 1704 represents a compilerthat is operable to generate x86 binary code 1706 (e.g., object code)that can, with or without additional linkage processing, be executed onthe processor with at least one x86 instruction set core 1716.Similarly, FIG. 17 shows the program in the high level language 1702 maybe compiled using an alternative instruction set compiler 1708 togenerate alternative instruction set binary code 1710 that may benatively executed by a processor without at least one x86 instructionset core 1714 (e.g., a processor with cores that execute the MIPSinstruction set of MIPS Technologies of Sunnyvale, Calif. and/or thatexecute the ARM instruction set of ARM Holdings of Sunnyvale, Calif.).The instruction converter 1712 is used to convert the x86 binary code1706 into code that may be natively executed by the processor without anx86 instruction set core 1714. This converted code is not likely to bethe same as the alternative instruction set binary code 1710 because aninstruction converter capable of this is difficult to make; however, theconverted code will accomplish the general operation and be made up ofinstructions from the alternative instruction set. Thus, the instructionconverter 1712 represents software, firmware, hardware, or a combinationthereof that, through emulation, simulation or any other process, allowsa processor or other electronic device that does not have an x86instruction set processor or core to execute the x86 binary code 1706.

What is claimed is:
 1. An apparatus comprising: a decoder circuit todecode an instruction, wherein the instruction to include at least anopcode field, a field for identifying a packed data source operand, anda field identifying for a packed data destination operand, the opcode toindicate a plurality of cumulative adds are to occur and a data elementsize of the packed data source operand to use in the cumulative adds;and execution circuitry to execute the decoded instruction according tothe opcode to, for each data element position of the source operand, addto a value stored in that data element position all values stored inpreceding data element positions of the packed data source operand andstore a result of the addition into a corresponding data elementposition of the packed data destination operand.
 2. The apparatus ofclaim 1, wherein the source operand is a packed data register and thedestination operand is a packed data register.
 3. The apparatus of claim2, wherein a single packed data register is used for the source anddestination operands.
 4. The apparatus of claim 1, wherein the dataelements of the source operand are stored in a little endian format. 5.The apparatus of claim 1, wherein the data elements of the sourceoperand are stored in a big endian format.
 6. The apparatus of claim 1,wherein the instruction to include a field writemask operand.
 7. Theapparatus of claim 6, wherein the execution circuitry to store a resultof the adds based on values of the writemask operand.
 8. An methodcomprising: decoding an instruction, wherein the instruction to includeat least an opcode field, a field for identifying a packed data sourceoperand, and a field identifying for a packed data destination operand,the opcode to indicate a plurality of cumulative adds are to occur and adata element size of the packed data source operand to use in thecumulative adds; and executing the decoded instruction according to theopcode to, for each data element position of the source operand, add toa value stored in that data element position all values stored inpreceding data element positions of the packed data source operand andstore a result of the addition into a corresponding data elementposition of the packed data destination operand.
 9. The method of claim8, wherein the source operand is a packed data register and thedestination operand is a packed data register.
 10. The method of claim9, wherein a single packed data register is used for the source anddestination operands.
 11. The method of claim 8, wherein the dataelements of the source operand are stored in a little endian format. 12.The method of claim 8, wherein the data elements of the source operandare stored in a big endian format.
 13. The method of claim 8, whereinthe instruction to include a field writemask operand.
 14. The method ofclaim 13, wherein the storing is based on values of the writemaskoperand.
 15. A non-transitory machine-readable medium storinginstructions which when executed to cause a processor to perform amethod, the method comprising: decoding an instruction, wherein theinstruction to include at least an opcode field, a field for identifyinga packed data source operand, and a field identifying for a packed datadestination operand, the opcode to indicate a plurality of cumulativeadds are to occur and a data element size of the packed data sourceoperand to use in the cumulative adds; and executing the decodedinstruction according to the opcode to, for each data element positionof the source operand, add to a value stored in that data elementposition all values stored in preceding data element positions of thepacked data source operand and store a result of the addition into acorresponding data element position of the packed data destinationoperand.
 16. The non-transitory machine-readable medium of claim 15,wherein the source operand is a packed data register and the destinationoperand is a packed data register.
 17. The non-transitorymachine-readable medium of claim 16, wherein a single packed dataregister is used for the source and destination operands.
 18. Thenon-transitory machine-readable medium of claim 15, wherein the dataelements of the source operand are stored in a little endian format. 19.The non-transitory machine-readable medium of claim 15, wherein the dataelements of the source operand are stored in a big endian format. 20.The non-transitory machine-readable medium of claim 15, wherein theinstruction to include a field writemask operand and the storing isbased on values of the writemask operand.